Recommendation for use: After two products have been commingled and the laboratory has tested the
fuels, the commingled product is blended with as an on-grade product to either return the properties to the
use limits of the original product or to downgrade the product. Most products can usually be recovered
assuming there is enough storage space within the tanks for the required blending. Blending should only
be done to meet use limits, and the product should be used as soon as possible after it has been certified
as meeting use limits by the laboratory.
Deterioration. Deterioration refers to changes occurring in a product while the product lies in storage.
Deterioration becomes more marked as the product ages, such as darkening of a product. It may be initiated or
hastened by the storage conditions. It is not normally noticed by personnel handling the product, as deterioration
of the product may not visibly affect the color or appearance. Discovery of deterioration is dependent upon an
adequate quality surveillance program. Most common forms of deterioration are weathering, gum formation, and
loss of additives.
Weathering. Weathering is due to evaporation of the more volatile components, referred to as "lights ends"
of a product. It is most noticeable in light products such as gasoline. Rate of evaporation increases markedly
with rises in temperature.
Storage tanks are vented to the air. Increase in evaporation produces pressures which force excessive
vapors to escape to the atmosphere through tank vents, thus allowing vapor loss. Lowering of the
temperature decreases vaporization, thus lowering tank pressures, and causing fresh outside air to be
drawn in to the tank through the vents. This operation is referred to as "breathing." Breathing may be
partially controlled by pressure-vacuum release valves on the tank.
Indication of deterioration by weathering: loss of volatile components, low RVP, high IBP. Effects: poor
starting of engines in cold weather. Recommendations for use: Blend with on-grade product at a
predetermined ratio, and use as soon as possible.
Gum. Gum formation is the most common and troublesome result of deterioration suffered by internal
combustion engine fuels. It is caused by the presence of unsaturated hydrocarbons in the presence of oxygen
undergoing chemical changes (polymerization of unsaturated hydrocarbons, the process of uniting light olefins to
form hydrocarbons of a higher molecular weight). Chemical changes produce a gummy material.
Gum materials are insoluble, are difficult to vaporize, clog jet and fuel lines, form deposits on valves,
cause incomplete combustion, and cause increased maintenance. After gummy material forms, a
resinous material forms which settles out on walls and bottoms of containers and is difficult to remove.
Oxidation inhibitors do not offer permanent protection. Indications of gum formations are darkening of
JP4, haze, or a gray cast in fuel. Oily gum is indication of contamination with heavier product. Dry gum is
indication of deterioration. Recommendation for use: Blend with on-grade product and use as soon as
possible.
Loss of Additives: Loss of additives such as tetraethyl lead (TEL), color, fuel system icing inhibitor (FSII),
or oxidation inhibitor means a loss in the performance of or in the management of the fuel.
Tetraethyl lead (TEL) loss is caused by long term storage or exposure to light. Effect on performance is
reduced power and engine knock. Indications of loss are a haze due to formation of lead and a low octane
rating or performance number. Recommendation for use: If precipitate will not settle, pass through a filter/
separator. If it meets engine tests and all other use limits, use as soon as possible. If filtering fails, blend
with on-grade product, or downgrade to meet TEL requirements and use as soon as possible.
Loss of color is caused by long-term storage/exposure to light. Effect: psychological effect on consumer
about the quality of the fuel and the management of the fuel during interfaces. Recommendation for use:
Use as soon as possible if product meets other test requirements.
Fuel system icing inhibitor (FSII) loss is caused by extraction by water while the fuel is in storage. This
loss effects the freezing point of water in the fuel. Ice can form in the fuel causing fuel line clogging which
causes engine flameout or stalling. Loss of additive is indicated by low FSII content and can be corrected
by blending with on-grade product or by reinjecting FSII.
Oxidation inhibitors found in light distillates. The additive is lost usually due to manufacturer's mistakes or
incompatibility of additives. Effect of the loss of this additive is gum formations in the fuel which will be
indicated by the gum test. Corrected by blending and using as soon as possible.
PART B - RECLAMATION/DISPOSITION PROCEDURES
4-3
QM 5184
Previous Page
